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Oseltamivir

Medication neuraminidase-inhibitor antiviral cold & flu
Aka: Tamiflu
Brands seen in Singapore: Tamiflu, Fluvir, Natflu, Seltavir, Starflu-75
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Prescribed for influenza type a and b — a doctor decides
When to take
FDA label: twice daily for 5 days when treating influenza
Take with
Water · HealthHub: with or without food
Pros & cons
Pros
  • HealthHub: capsules may be opened if swallowing is hard
  • FDA label: the adult treatment course is 5 days
  • HealthHub: breastfeeding can be continued on it
Cons
  • HealthHub: nausea, vomiting or diarrhoea are common
  • HealthHub: rare confusion, delirium, hallucinations
  • HealthHub: not a substitute for influenza vaccination
Sources
  1. HSA — Listing of Registered Therapeutic Products (data.gov.sg open dataset, 5,511 rows, pulled in full via datastore_search and filtered locally) · read 2026-08-27
    what it says
    “All 11 registered oseltamivir products carry Forensicclassification 'Prescription Only' — SIN11403P TAMIFLU CAPSULE 75 mg · SIN16307P FLUVIR · SIN16241P NATFLU · SIN16667P SELTAVIR · SIN15685P STARFLU-75”
  2. HealthHub (Pharmaceutical Society of Singapore / National Medication Information workgroup) — Oseltamivir: what is this medication for · read 2026-08-27
    what it says
    “Oseltamivir is used to prevent or treat infections caused by influenza viruses (Type A and B). It is an antiviral medication … Oseltamivir is not a substitute for influenza vaccination.”
  3. HealthHub — Oseltamivir: how should I take or use this medication · read 2026-08-27
    what it says
    “You may take Oseltamivir with or without food. The capsules may be opened to provide the correct dosage when given for a child or for those who cannot swallow.”
  4. HealthHub — Oseltamivir: precautions, pregnancy and breastfeeding · read 2026-08-27
    what it says
    “Inform your healthcare professional if: You are allergic … You are pregnant … there are limited studies in pregnant women … Breastfeeding while taking Oseltamivir can be continued.”
  5. HealthHub — Oseltamivir: common side effects · read 2026-08-27
    what it says
    “You may experience nausea, vomiting or diarrhea … You may experience dizziness … You may experience headache.”
  6. HealthHub — Oseltamivir: rare but serious side effects · read 2026-08-27
    what it says
    “Neuropsychiatric reactions such as: Confusion; Delirium; Hallucinations or unusual thoughts or behavior … Symptoms of a drug allergy … Swollen face/eyes/lips/tongue; Difficulty in breathing”
  7. HealthHub — Oseltamivir: what food or medication should I avoid · read 2026-08-27
    what it says
    “Live influenza vaccine should be avoided within 2 weeks before or 48 hours after administration of Oseltamivir unless medically indicated. Avoid using Oseltamivir together with Probenecid.”
  8. US FDA label for TAMIFLU (oseltamivir phosphate), section 2 Dosage and Administration, via openFDA drug/label.json (effective 2025-12-15) · read 2026-08-27
    what it says
    “Adults and adolescents (13 years and older): 75 mg twice daily for 5 days … Prophylaxis … 75 mg once daily for at least 10 days … Community outbreak: 75 mg once daily for up to 6 weeks”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.